Abstract: A bilateral transmission line repeater is disclosed in which opposite directions of transmission are separated into different frequency bands. The amplifiers for each direction of transmission include an automatic gain control circuit for controlling the gain of the amplifier. Gain control for the inward bound amplifier (toward a central location such as a telephone central office) is under the control of an automatic gain control signal derived from the outward bound signal as well as from the inward bound signal. Feedback around the gain control amplifier is accomplished using a current mirror circuit to avoid loading the amplifier output.

Abstract: A telephone central office main frame system is disclosed in which jumper wire terminations are placed by an automatic mechanism in response to control signals. The terminals are laid out in vertical lines having troughs therebetween in which the jumper wires lie. By alternating rows of input and output terminals, a large degree of flexibility of interconnection is obtained. In particular, a rotating pick-up head secures a twisted jumper wire pair from a reel source, automatically terminates one end of the wire pair in one set of preselected terminals, runs the jumper wires through the trough to the vicinity of the other terminals and, finally, automatically terminates the other ends in the preselected terminals.

Abstract: A high stability integratable resistance-capacitance oscillator is disclosed which is capable of operating at a stable frequency regardless of changes in ambient temperature or applied voltages. The oscillator uses a temperature compensating impedance and semiconductor junction to compensate for temperature dependent variations in active elements of the oscillator. Constant current bias sources and voltage clamping circuits insure oscillations having predetermined amplitude ranges despite changes in applied voltages. Active transistors in the oscillator are maintained in their linear range by the use of antisaturation transistors connected between their base and collector electrodes.

Abstract: A power converter circuit is disclosed utilizing pulse width modulation for power regulation. A rapid acting surge protection circuit for the power driving switch is operated from a string of zener diodes to disable the power switch. A base charge removal circuit is included for removing accumulated base charges on the driving transistor without the need for a bipolar driving signal for the power transistor.

Abstract: A bilateral repeater for communication transmission lines is described in which the opposite directions of transmission are separated by frequency bands for amplification. The repeater is powered from a power conversion unit energized from the line potential. The repeater includes three-electrode gas tube breakdown devices connected across the repeater for each conductor of the transmission line. The third electrodes in the gas tubes are cross-connected together with no ground connection.

Abstract: A power supply for developing substantially constant average power in a variable resistance load (18) from an alternating polarity source (11) comprises an AC portion including serially connected capacitor means (12), and a DC portion including rectifying means (20) for providing a polarized signal to load resistance (18) and inductor means (17) for maintaining a charging current through a path including capacitor means (12). The constant average power mode obtains when the range of values of load resistance (18) is less than a network parameter determined from the frequency of source (11) and value of capacitor means (12).

Abstract: A hands-free telephone system is disclosed utilizing an infrared transmitter and receiver to permit wireless speech transmission. The transmitter uses frequency modulation imposed on the infrared signal and includes carrier shift signaling arrangements for indicating a low battery condition and transmitter turn-off. The receiver utilizes a noise detection circuit for permitting remote turn-on, for squelching noise in the voice path, and for feeding an alerting signal to a loudspeaker to indicate that the received signal is excessively noisy. The portable transmitter must then be moved or redirected to provide a better line-of-sight signaling path.

Abstract: A ringing signal generator is disclosed for remotely generating telephone ringing signals having a trapezoidal waveform. A single capacitor and two constant current sources control the wave shape while current limiting is provided on both the positive going and negative going half-cycles of the ringing signal. A voltage offset is provided between the ringing signal source and the subscriber line to prevent loading the ringing signal with the subscriber line feed circuit.

Abstract: A ring trip detection circuit is disclosed for a remotely generated ringing signal in a subscriber loop carrier system. The ring trip detection circuit is enabled only during the high voltage half-cycle of the ringing signal to increase ring trip detection sensitivity and reduce the size and complexity of the ring trip detection circuit.

Abstract: A bilateral transmission line repeater is disclosed in which opposite directions of transmission are separated into different frequency bands. The amplifiers for each direction of transmission include an automatic gain control circuit for controlling the gain of the amplifier. Gain control for the inward bound amplifier (toward a central location such as a telephone central office) is under the control of an automatic gain control signal derived from the outward bound signal as well as from the inward bound signal. Feedback around the gain control amplifier is accomplished using a current mirror circuit to avoid loading the amplifier output.

Abstract: A hands-free telephone system is disclosed utilizing an infrared transmitter and receiver to permit wireless speech transmission. The transmitter uses frequency modulation imposed on the infrared signal and includes carrier shift signaling arrangements for indicating a low battery condition and transmitter turn-off. The receiver utilizes a noise detection circuit for permitting remote turn-on, for squelching noise in the voice path, and for feeding an alerting signal to a loudspeaker to indicate that the received signal is excessively noisy. The portable transmitter must then be moved or redirected to provide a better line-of-sight signaling path.

Abstract: A relay driver circuit is disclosed in which a relay coil is operated by enabling the collector-emitter path of a switching transistor. In order to avoid damage to the transistor from voltages induced in the relay coil when the relay is turned off, an isolating semiconductor device is inserted between the transistor and the relay coil. This semiconductor device is operated in synchronism with the driving transistor and thus isolates the driving transistor from transients during the de-energization of the relay.

Abstract: A subscriber loop carrier system is disclosed in which a plurality of telephone subscriber communications channels are frequency-multiplexed on a single wire pair using analog modulation techniques. Supervisory signaling for each channel is accomplished by modulating the channel carrier with a plurality of tones coded so as to represent a plurality of supervisory functions including multiparty superimposed ringing (four-party fully selective, eight-party semiselective), two-party ringing and tip party identification, and standard single party ringing, as well as off-hook and dial pulse superivision. The system is designed to be universally compatible with any of the above classes of service.

Abstract: A hands-free telephone system is disclosed utilizing an infrared transmitter and receiver to permit wireless speech transmission. The transmitter uses frequency modulation imposed on the infrared signal and includes carrier shift signaling arrangements for indicating a low battery condition and transmitter turnoff. The receiver utilizes a noise detection circuit for permitting remote turn-on, for squelching noise in the voice path, and for feeding an alerting signal to a loudspeaker to indicate that the received signal is excessively noisy. The portable transmitter must then be moved or redirected to provide a better line-of-sight signaling path.

Abstract: A power converter circuit is disclosed utilizing pulse width modulation for power regulation. A rapid acting surge protection circuit for the power driving switch is operated from a string of zener diodes to disable the power switch. A base charge removal circuit is included for dissipating accumulated base charges on the driving transistor without the need for a bipolar driving signal for the power transistor.

Abstract: A method and apparatus for semiautomatic wiring of telephone cabinets is disclosed which is suitable for twisted pairs of telephone wires. A pair-indexing head having a plurality of dual threaded spinning index rotors is used to permit automatic mass-termination of the individual wires in slotted-beam connectors. By pulling the connector block and attached wires down the length of the electrical cabinet, indexing the tip and ring conductors at the desired length, providing clamps at both ends of the twisted pairs, and cutting the wires, an operator is able to take the wires, one pair at a time, with proper tip and ring orientation, and terminate them on the back wiring plane of the electrical cabinet. The connector is then dressed through a wiring channel to exit at one end of the wiring cabinet and provide an easy means for connecting the cabinet to external wiring.

Abstract: A testing and recording system is disclosed for determining and recording the cable pair-line equipment assignments in a telephone central office. Using a multipair shoe on the main frame appearances of the cable pair, an off-hook condition is simulated successively on each of a plurality of idle cable pairs. At the same time, the dial tone markers are monitored to determine which line equipment responds to the off-hook condition. If the off-hook test condition is of very brief duration and takes place during times of low central office traffic, there is a high probability that only one off-hook condition will occur during the test interval. If only one dial tone marker response occurs during this brief interval, the cable pair identification and line equipment identification are recorded to create a record of this assignment. Alternatively, a tone associated with each dial tone marker is detected to ascertain which marker responded to the simulated off-hook condition.

Abstract: Conventional delta modulation techniques ignore information contained in the input signal which may be used advantageously in the encoding process. Improved delta modulation methods are disclosed which reduce bit rate and enhance error performance by partitioning the input signal into variable-length segments determined by preselected characteristics of the signal. Within each segment, iterative encoding is employed to develop the bit stream representing the encoded input signal. One particular partitioning method employs positive and negative signal peaks to establish segment boundaries and the encoding process is aided by the gradient of the signal within each segment.

Abstract: A subscriber loop carrier system is disclosed for frequency multiplexing a plurality of subscriber channels on a single twisted metallic pair using frequency division techniques. Supervisory signaling is accomplished from the central office to a remote location by imposing a signaling tone of the carrier frequency for each signal. Supervision from the remote terminal to the central office is accomplished by interrupting the carrier signal itself. Ringing signals are supplied by interrupting the tone signal at a 20 Hz rate. Testing the subscriber channel is accomplished by leaving the tone on for a period in excess of the period used for ringing. Each channel of the carrier system can, therefore, be independently tested by using the uninterrupted tone to gate the remote carrier on for transmission back to the central office terminal. When detected, this carrier signal from the remote terminal indicates a complete communication path from the central office to the remote terminal and back again, i.e.

Abstract: Apparatus and methods are disclosed for defining and controlling the relative positioning of symbols in a computer-based imaging system for generating images suitable for controlling a printing operation. Information describing the symbols is stored in a memory and is retrieved and the corresponding symbol relatively positioned on an imaging device in response to a control program and an input specification of the desired coincidence of "concatenation points" associated with each symbol.